1. Field of the Invention
Embodiments of the present invention generally relate to a hand tool and more particularly to a vise. More particularly still, embodiments of the invention relate to a table top mounted vise with improved performance and utility.
2. Description of the Related Art
Vises are used in order to temporarily hold one or more objects so that work can be performed on them. Traditional table top mounted vises have existed for years. A typical vise is composed of a stationary jaw with a base that can be mounted to a surface. There is a moveable jaw and a guide rod(s) that allows the moveable jaw to move smoothly toward and away from the stationary jaw. Each jaw has a clamping surface for holding a work piece. Further, the vise has a screw and lever system which operates the moveable jaw. The screw typically has a relatively fine pitched thread which provides a large mechanical advantage such that a relatively small amount of torque applied to the lever produces a large clamping force between the jaws. The screw moves the moveable jaw whereby the fine pitch required for the large mechanical advantage causes the jaw to move a very small distance with each turn. Thus, adjusting the jaws to different opening sizes for clamping of relatively thin and subsequently relatively thick items (or vice versa) requires numerous turns of the lever attached to the screw.
Recent developments in vises have allowed for a quicker adjustment of the vise. The vise designs have generated solutions that allow the fine pitched thread mechanism to be disengaged while allowing rough adjustments of the vise head. Where the traditional vise had a female thread integral to the stationary jaw that engaged with the screw, these new vises have a female thread part separate from the stationary jaw. The separate part is called a semi-thread because it engages with less than 180° of the screw. The semi-thread rides in a track system in the stationary head such that a mechanism can disengage the semi-thread from the screw as desired. With the semi-thread disengaged, a user can slide the moveable jaw to the approximate opening size required for application at hand. A separate lever on the moveable jaw turns a bar or shaft that subsequently disengages the semi-thread from the male thread. The semi-thread is typically spring loaded into engagement with the male thread. With the semi-thread disengaged the jaw opening can be adjusted to the desired size. This system is a vast improvement over previous vises, increasing the efficiency of use.
However, there are several problems with the prior art. The prior art requires two levers to operate. One lever is required to turn the bar and subsequently disengage the semi-thread. While holding this lever in position to keep the semi-thread out of engagement, the jaw opening can be adjusted to the appropriate size by pulling or pushing on the moveable jaw. To apply large clamping force the user must let go of this first lever and grab the second lever that turns the screw to apply a significant clamping force.
Therefore, a need exists for an improved apparatus and method of vise clamping that would allow a user to quickly adjust the opening size of the jaws and apply clamping force to the jaw through the use of one lever.